The invention is directed to a propellant of reduced combustibility for aerosols, a process for producing it and an apparatus for carrying out the process.
They are known as propellants of reduced combustibility for aerosols fluoro-chloro-hydrocarbon gases which until now have been used to a great extent and even still are in use. However, it appears that their use is not completely unobjectionable since at least there exists the possibility that with a persistent and large discharge into the earth's atmosphere there takes place an attack on the ozone belt surrounding the earth. This is significant in the absorption of UV rays. Thus different concerned agencies have even considered forbidding the use of this type of propellant for aerosols.
It is also known to use untreated hydrocarbons as propellants for aerosols. However, since these above all are readily combustible their use is problematical. Of course it is also known to reduce the combustibility of hydrocarbons which are to be used as propellants by addition of materials less susceptible to oxidization, e.g. by addition of nitrous oxide, yet with this alone there have not been produced satisfactory results.
It is even known to reduce the combustibility (flammability) of hydrocarbons by adding water. However, this has the disadvantage that water at the same time acts as a disturbing ballast material, since it practically does not volatilize and cannot assist the propellant in its true function. Instead it is much more likely to favor a phase separation which naturally is undesired. Finally the addition of water in tinplate promotes the corrosion of the same.
It is known from British Pat. No. 1,476,117 to use as propellant for aerosol deodorants, for example a mixture of C.sub.3 -C.sub.4 hydrocarbons and methylene chloride. However, there are no statements in regard to the percentage composition of this type of mixture and of its flammability.
It is now the object of the invention to propose a propellant with reduce flammability which on the one hand is not feared as attacking the ozone belt in the suspected manner and on the other hand is reduced in its flammability in a comparable manner with fluoro-chloro-hydrocarbon gases without being mentionably damaged in its propellant action. Furthermore, the invention should provide a process for production of such a propellant as well as an apparatus for carrying out the process.